//https://leetcode.cn/problems/fan-zhuan-lian-biao-lcof/description/

struct ListNode* trainningPlan(struct ListNode* head) {
    struct ListNode* cur = head;
    struct ListNode* prev = NULL;
    while (cur)
    {
        struct ListNode* next = cur->next;
        cur->next = prev;
        prev = cur;
        cur = next;
    }

    return prev;
}